[Wordpress issuses] dernabelderwelt on "all layout is gone, whole site just in html"

Hello guys,
i checked my blog after long time. I am a newbie, and i really have no idea what happend. The whole site, user and reader-areas are shown in a kind of html. I have no formated dashboard, and its not possible to change the theme. Checked(and cleaned cache) in chrome, explorer and mozilla all the same. Updated java and flash no change.

I have no idea what is going on and I need help. Can some one give me a hint, an idea where to search or read, or what to do?

Thanks Holger

The blog I need help with is dernabelderwelt.wordpress.com.

.

forums.wordpress.com